Braga dominated the first hour of the game and went ahead early in the second half when Alan converted a penalty for the hosts.

But, following a power cut just before the hour mark, United returned to the pitch and turned the match around in the final ten minutes thanks to goals from Van Persie, a spot kick from Wayne Rooney and a late strike from Chicharito.

Chris Smalling made his first appearance of the season as United made six changes from the weekend win over Arsenal. Van Persie dropped to the bench with Sir Alex Ferguson opting for the front pairing of Danny Welbeck and Chicharito, while Antonio Valencia played as a make shift right-back. Braga coach Jose Peseiro selected the same side which lost the return fixture at Old Trafford.

The hosts had the first sight on goal in the fifth minute when Eder flashed a shot across David De Gea from a wide angle after Johnny Evans allowed the Braga forward to skip into the area unopposed.

United managed to settle into the match following the early scare, but it was Braga who again came closest to scoring when Ruben Michel was invited to shoot by United's retreating defence, but the midfielder could only curl his shot a yard wide of the top corner.

Michel continued to find space in the visitors’ half and Braga almost reaped the rewards when Eder's low diving header, from Michel's cross, hit the post with De Gea beaten.

The hosts began the second period how they ended the first and were awarded a penalty only three minutes after the restart when Evans blocked off Custodio's run into the box. Alan stepped up and emphatically converted to give Braga a deserved lead.

A power cut in the 57th minute delayed the game temporarily, with both sets of bemused players leaving the field of play while officials worked on the stadium's floodlights.

Rio Ferdinand replaced Evans when the game resumed, with Van Persie also coming on for Welbeck shortly after, as United pressed for an equaliser. Braga began to sit deep in their half after going ahead but continued to pose a threat on the break.

Sir Alex's charges began to show signs of life as the match edged into the final ten minutes and had opposition goalkeeper Beto to thank for levelling the scores when he rashly ran out of his area to halt Van Persie, only for the Dutchman to whip the ball out of his reach and into the empty net.

And moments later the turnaround was complete. United were awarded a penalty after Rooney was brought down in the area, a spot-kick the forward dispatched with ease.

Chicharito added a late third for the visitors in injury time with a close-range finish to seal United’s progression to the next stage with a 100 per cent record.